woe to (one)
1. Misfortune or unpleasant consequences await or will happen to one (if something happens). The legislation is becoming increasingly complex, and with enforcement tightening all the time, woe to anyone who fails to familiarize themselves with every letter of the law. All I can do is offer my advice as to the best and safest course of action—woe to you if you decide to ignore it.
2. One deserves great punishment or misfortune. Woe to you, Mr. Smith, for destroying the lives of so many employees and dragging the reputation of a once-mighty company through the mud.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
woe to (someone)
1. Used to express the wish for someone to experience misfortune.
2. Used as a warning or allusion to negative consequences: "Our sun will be a red giant, and woe to any earthlings who may be around to witness its bloated blush, for the planet on which they stand will likely be vaporized in the expansion" (Natalie Angier).
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.